April 1, 2013
by Edward Lowe, BSc., DMD, FICOI, FACD
INTRODUCTIONPlacing composite restorations in the posterior region can be a time-consuming and technique sensitive procedure. Historically, clinicians have used traditional direct composites to complete these restorations, carefully layering, sculpting, and curing 2mm increments. This process, while still used today due to its prevalence, presents several difficulties to the clinician, primarily in the form of polymerization shrinkage and the corollary shrinkage stress.1 These difficulties can cause stress fractures at the margins, marginal leakage, or an increased likelihood of secondary caries and post-procedural sensitivity,2 ultimately leading to clinical failure of the restoration.
In an attempt to alleviate some of the inherent difficulties with direct composites, dental manufacturers introduced flowable composites. Flowable composites are placed using a method in which a clinician applies a thin layer of resin-based glass ionomer material to the floor of preparations before applying bonding agents. Next, the flowable composite is applied and light cured. Then, a “capping layer” of direct composite was still needed to create suitable anatomical form. While this technique did save some time and was less difficult, polymerization shrinkage led to loss of adhesion in the tooth-to-restoration interface and, therefore, shrinkage stress, marginal leakage, and recurrent caries were still problematic.3
The continued search for a more efficient and less technique-sensitive procedure led to the invention of bulk fill composites. These materials allowed clinicians to fill and cure preparations up to 4mm deep in one increment. Unfortunately, the first generation of bulk fills contained oversized filler particles that led to premature wear, fracturing, and failure.4 They also were often available in only one highly translucent shade that appeared grey next to natural dentition.
Some of these materials also had a high reactivity to ambient operatory light, and this severely limited the amount of time the clinician had to perform the restorative procedure, and the esthetics could suffer.
NEW BULK FILL MATERIALSThe next logical progression was to create a bulk fill composite that still exhibited high strength characteristics but had greater esthetics and manipulability. This was achieved by altering the size of the filler particles. Modern bulk fills are typically micro-filled, meaning the size of the filler particles are much smaller. This allows for a bulk fill material with a greater depth and uniformity of cure,5 a smooth consistency, life-like optical properties, and easier sculpting of anatomic form without requiring an additional “capping layer”.6
TETRIC EVOCERAM BULK FILLNow there’s Tetric EvoCeram Bulk Fill (Ivoclar Vivadent, Amherst, NY). Tetric EvoCeram Bulk Fill exhibits a true advancement in bulk fill technology. One of the innovations featured in this product is the inclusion of the patented light-initiator Ivocerin. This new germanium-based light initiator allows a complete, homogenous cure in just 10 seconds using basic curing lights. One of the components of Ivocerin is an ambient light immunizer that assures ample working time for the clinician to create artistic anatomical form.
Tetric EvoCeram Bulk Fill also contains a shrinkage stress reliever, eliminating the worries of shrinkage stress, since forces are evenly distributed across cavity walls and surfaces. Volumetric shrinkage of the material is also very low, which provides a more predictably placed restoration. The layered silicates that form the bulk of this material provide a smooth consistency, which facilitates optimal adaption to cavity walls and easy contouring with conventional dental instruments.
This composite is available in three universal shades (IVA for slightly reddish teeth; IVB for slightly yellowish teeth; and IVW for quick deciduous fillings or lightly-colored teeth) and has a life-like translucency of 15%.
This material also demonstrates excellent radiopacity for high visibility on x-rays. Tetric EvoCeram Bulk Fill is an alternative procedure that takes half the time but still produces posterior restorations that are strong, predictable, and blend seamlessly with natural dentition.
The following presentation demonstrates two effective bulk fill methods for posterior composite restorations compared to tradition layering and the time required to complete each procedure.
CASE PRESENTATIONA healthy 45-year-old male patient presented with occlusal amalgam fillings that were placed more than 20 years previously. A treatment plan was agreed upon involving the restoration of teeth #4.6 and #4.8 using a bulk fill composite (Tetric EvoCeram Bulk Fill), and tooth #4.7 using both a flowable and universal composite (Tetric EvoFlow and Tetric EvoCeram).
One of the three universal shades most closely matching the patient’s dentition is chosen (Fig. 1). This patient was well matched to shade IVA (for slightly reddish teeth). After inspecting the old amalgam restorations (Figs. 2 and 3), a rubber dam was then placed (Fig. 4). Next, using a carbide bur, the amalgam restorations and all damaged tooth structure were removed (Figs. 5 and 6). All remaining sharp edges of the preparation were then beveled with a fine finishing diamond (Fig. 7), completing the preparations (Fig. 8).
A self-etch dental adhesive (AdheSE One F, Ivoclar Vivadent) was applied to tooth #4.6 using the VivaPen delivery system (Figs. 9 and 10), leaving a shiny bonded surface (Fig. 11). A stream of oil-free, moisture-free air expelled from a warm air tooth dryer (Adec) was then directed over the adhesives to evaporate the solvent (Fig. 12). The adhesive was light-cured with the an LED curing light (Bluephase Style, Ivoclar Vivadent) for 10 seconds (Fig. 13).
A single increment of Tetric EvoCeram Bulk Fill in shade IVA was then placed in the preparation of tooth #4.6 (Fig. 14), and shaped first with an OptraSculpt sphere attachment (Fig. 15), then with an OptraSculpt pyramid attachment (Fig. 16). The final anatomy was contoured using a P1 carver (Fig. 17). As a final step before finishing, the restoration was light-cured with the LED curing light (Figs. 18 and 19).
Preparation then began on tooth #4.7. Etchant (Total Etch, Ivoclar Vivadent) was applied to the enamel and allowed to penetrate for 15 seconds, after which the etchant was applied to the dentin and allowed to penetrate for 10 seconds to ensure proper etching of both surfaces (Figs. 20 and 21). The etchant was then rinsed off with water, and all excess moisture was removed (Fig. 22). A total-etch dental adhesive (Excite F) was then applied to the preparation and agitated for 10 seconds (Fig. 23). A stream of warm air was expressed onto the adhesive to evaporate the solvent (Fig. 24), and the adhesive was light-cured using the LED curing light (Bluephase Style) for 10 seconds (Fig. 25).
Tetric EvoFlow shade A3 was flowed 0.5mm thick onto the floor of the preparation of tooth #4.7 and light-cured for 10 seconds (Fig. 26). Then, a layer of Tetric EvoCeram shade A3 was placed within 0.5-1mm of the cavosurface margin. This second layer was shaped to replicate the dentin layer, then light-cured for 10 seconds (Figs. 27 and 28). Tetric EvoCeram Transparent was then used to create each of the four triangular ridges of the natural tooth, and each ridge was subsequently light-cured for 10 seconds (Figs. 29 and 30).
Lastly, preparations began on tooth #4.8 by applying the Total Etch phosphoric acid to the enamel and allowing 15 seconds for penetration, then applying the etchant to the dentin and allowing 10 seconds for penetration (Fig. 31). Then, the etchant was completely rinsed off, leaving the area moist. Excite F dental adhesive was then applied (Fig. 32), and a warm stream of air was directed over the preparation to evaporate the solvent. The Excite F adhesive was then light-cured for 10 s
One increment of Tetric EvoCeram Bulk Fill shade IVA (for slightly reddish teeth) was then delivered to tooth #4.8 (Fig. 33). An OptraSculpt sphere was then implemented to sculpt the composite to the floor and walls of the preparation (Fig. 34), after which an OptraSculpt pyramid was used to further form the tooth shape (Fig. 35). The restoration, now fully formed, was light-cured with the LED curing light (Bluephase Style) for 10 seconds (Fig. 36). Note that the shape of the light’s tip allowed easy access to the tight space. A fine, tree-shaped diamond, similar in shape to the P1 carver, was then used to establish occlusal anatomy (Fig. 37).
An OptraPol NG polishing instrument was utilized to polish the completed restorations of all three teeth to a high-gloss (Figure 38). After polishing, the rubber dam was removed (Fig. 39 and 40), and articulating paper was used to check the patient’s occlusion (Figs. 42 and 43). The occlusion was determined to be satisfactory and the restorations complete (Figs. 44 and 45).
The patient returned the following week for a follow-up visit and reported no post-procedural sensitivity. After re-hydration, the excellent color-matching to the patient’s natural dentition was visible, and all three restorations appeared very similar esthetically.
CONCLUSIONThis case illustrates the different reliable methods for posterior restoration placement. Which material is chosen by the clinician only depends on the speed with which the restoration needs to be completed. As the materials and processes used to complete posterior restorations have progressed, they have become increasingly more efficient, esthetically pleasing, and predictably placed. In this case, the clinician used Tetric EvoFlow and Tetric EvoCeram A3 to place the restoration on tooth #4.7, and the procedure took 7 minutes. The clinician used Tetric EvoCeram Bulk Fill IVA on teeth #4.6 and #4.8, and these restorations were placed in just over 4 minutes each. This proves that Tetric EvoCeram Bulk Fill allows completion of a class II restoration in half the time, with great results.OH
Dr. Edward Lowe maintains a full time private practice devoted to comprehensive functional aesthetic and reconstructive dentistry in downtown Vancouver, BC.
REFERENCES1. Giachetti L, Scaminaci-Russo D, Bambi C, Grandini R. A review of polymerization shrinkage stress: current techniques for posterior direct restorations. J Contemp Dent Pract. 2006;7(4):79-88.
2. Cheung GS. Reducing marginal leakage of posterior composite resin restorations: a review of clinical techniques. J Prosthet Dent. 1990;63(3):286-288.
3. Christensen GJ. Remaining challenges with class II resin-based composite restorations. J Am Dent Assoc. 2007;138(11):1487-1489.
4. Lutz F, Phillips RW, Roulet J-F, Imfeld T. Composites klassifkation und wertung. Schweiz Mschr Zahnheik. 1983;93:914-929.
5. Polydorou O, Manolakis A, Hellwig E, Hahn P. Evaluation of the curing depth of two translucent composite materials using a halogen and two LED curing lights. Clin Oral Invest. 2008;12:45-51.
6. Ferrcane JL. Resin composite- state of the art. Dent Mater. 2011;27(1):29-38. Epub Nov 18, 2010.
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